Field of the Invention
The present invention relates to a zoom-type lens barrel mounted on an image pickup apparatus such as a digital camera, and an image pickup apparatus equipped with the zoom-type lens barrel.
Description of the Related Art
There has been proposed a zoom-type lens barrel mounted on an image pickup apparatus such as a digital camera, which rotates a cam cylinder to move a lens holder, which is engaged with a cam groove of the cam cylinder, in a direction of an optical axis (Japanese Laid-Open Patent Publication (Kokai) No. 2015-4759). According to this proposal, driving force of a motor unit, which is provided on an outer side of the cam cylinder in a radial direction, is decelerated and transmitted to the cam cylinder via a gear train, causing the cam cylinder to be rotatively driven.
There has also been proposed a zoom-type lens barrel which drives a lens holder, which is supported movably in a direction of an optical axis by a guide bar, using a drive unit such as a stepping motor, in the direction of the optical axis (Japanese Laid-Open Patent Publication (Kokai) No. 2007-271649). According to this proposal, stepping motors corresponding in number to the number of lens groups constituting a shooting optical system are provided to drive the lens groups independently of one another.
According to Japanese Laid-Open Patent Publication (Kokai) No. 2015-4759 mentioned above, however, the cam cylinder which drives the lens holder in the direction of the optical axis is rotatively driven by the motor unit provided on the outer side of the cam cylinder in the radial direction, and this brings about an increase in a size of the lens barrel in a radial direction. On the other hand, according to Japanese Laid-Open Patent Publication (Kokai) No. 2007-271649 mentioned above, there is flexibility in a shape of the lens barrel, and for example, the lens barrel should not necessarily have a cylindrical shape, but the stepping motors corresponding in number to the number of lens groups are needed, and this presents a problem because the size of the lens barrel increases, and control over the motors becomes complicated.